How does negative work on a system occur?
1 answer:
Answer:
The negative work is done in the opposite direction of the movement.
Explanation:
When the force applied to the body acts contrary to the movement of the body, it is considered that a negative mechanical work is performed.
In the attached image, we can see how these forces acting over one body.
In the sketch we can see how the force is moving the block to the right, it means in the direction of the movement and the friction force is acting in the opposite direction of the movement, that is the reason that the work is negative.
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Answer:
a) 3.43 m/s
Explanation:
Due to the law of conservation of momentum, the total momentum of the bullet - rifle system must be conserved.
The total momentum before the bullet is shot is zero, because they are both at rest, so:
Instead the total momentum of the system after the shot is:
where:
m = 0.006 kg is the mass of the bullet
M = 1.4 kg is the mass of the rifle
v = 800 m/s is the velocity of the bullet
V is the recoil velocity of the rifle
The total momentum is conserved, therefore we can write:
Which means:
Solving for V, we can find the recoil velocity of the rifle:
where the negative sign indicates that the velocity is opposite to direction of the bullet: so the recoil speed is
a) 3.43 m/s